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- // Copyright (C) 2003, Fernando Luis Cacciola Carballal.
- // Copyright (C) 2014, 2015 Andrzej Krzemienski.
- //
- // Use, modification, and distribution is subject to the Boost Software
- // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- //
- // See http://www.boost.org/libs/optional for documentation.
- //
- // You are welcome to contact the author at:
- // fernando_cacciola@hotmail.com
- //
- #ifndef BOOST_NONE_T_17SEP2003_HPP
- #define BOOST_NONE_T_17SEP2003_HPP
- namespace boost {
- #ifdef BOOST_OPTIONAL_USE_OLD_DEFINITION_OF_NONE
- namespace detail { struct none_helper{}; }
- typedef int detail::none_helper::*none_t ;
- #elif defined BOOST_OPTIONAL_USE_SINGLETON_DEFINITION_OF_NONE
- class none_t {};
- #else
- struct none_t
- {
- struct init_tag{};
- explicit none_t(init_tag){} // to disable default constructor
- };
- #endif // old implementation workarounds
- } // namespace boost
- #endif // header guard
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